We will continue to make three-dimensional eye rotation measurements in normal and strabismic subjects using a new photographic and psychophysical after-image technique. In normals we will assess how eye torsion varies in different fields of gaze under different circumstances, such as during head tilt and convergence. We will make similar measurements in strabismic patients and will look for characteristics deviations from Listing's Law, in order to correlate these deviations to specific disorders. We will also compare the results of these measurements with a theoretical analysis of extraocular muscle action. BIBLIOGRAPHIC REFERENCES: Nakayama, K. Coordination of extraocular muscles. In, Basic Mechanisms of Ocular Motility and Their Clinical Implications, G. Lennerstrand and P. Bach-y-Rita (Eds.) Oxford, England, Pergamon Press, Ltd. 1975, pp 193-207.